Separately:
I liked the old MM. I didn't mind the way it worked or how unbalanced it was. It was crazy and you really never knew what might occur. Now, to be fair, I don't have a problem with ONLY +/-2 MM and tiers 1-3 seeing only +/-1. That's fine, I guess, but it takes the variety of what might occur RIGHT OUT. In some (many) ways, that may be a good thing. I just liked how insane the MM was back then, because sometimes it was just amazingly frustrating -- and then, somehow, your team would win something you thought unwinnable on it's face, six heavy, four tank destroyers, two lights a medium and two arty -- what? -- that kind of insane, being matched against something like two heavy, six medium, three tank destroyers a two lights and two arty.
That's the sort of stuff that made, in my view, the matchmaking awesome. You couldn't count on meeting a balanced by unit team and if you did, it was usually wildly crazy in the distribution of skill anyway. Literally anything could happen.
That was its appeal to me.
I think balancing for tiers to keep it more even is probably a good idea, even though I liked the old MM. I would be okay with some set of balancing algorithms, like 3/5/7, then also, say, 5/5/5, 4/6/5, 7/8, 2/4/9 might even be fun. Maybe have them set to 'rotate' every forty minutes or thirty minutes or so, in order that all the algorithms get used, maintaining a semblance of greater variety in matching and battle types without tossing out the entire tiering concept that makes this game what it is in terms of challenge.
I don't mind it the way it is, though I have to admit, I miss the old MM in it's entirety. I have found nothing in the new MM that makes me go, "Well, gosh darn it, I think this New MM is the Bee's Knees!" And you can quote me on that. It's okay. I do know that I am more often now bottom tier than I was before, though I don't really mind that usually. Felt pretty much like that when I played the Leopard or Chaffee and saw tier tier VIIIs regularly. You get used to it.
GL, HF & HSYBF